Tuesday, 9 November 2010

Hop additions - is this the end?

Quite a long quote today. But it's from a brewing classic "Scottish Ale Brewer" by W.H. Roberts. A book which, through no fault of its own, has indirectly led to some of the more popular myths about Scottish beer. Particularly in regard to hopping.

This bit in particular:

"With regard to the quantity of hops which the brewers in Scotland use for each quarter of malt, it is impossible to fix any certain data, as it varies from four to eight pounds, according to the quality of the ale, and the season of the year. In winter-brewings, six pounds of hops for the best ale, and four for the inferior kinds, may be considered a fair estimate."
"Scottish Ale Brewer", W.H. Roberts, 1847, page 89.

These hop rates are on the low side, but not exceptionally so. Whitbread's X Ales of this period had between 6 and 9 pounds of hops per quarter. Barclay Perkins X Ales, between 7 and 10 pounds per quarter. William Younger between 4 and 9 pounds per quarter in its shilling Ales.

"Our practice in brewing, from January to March, was, to allow ten pounds of hops per quarter of malt, when the wort was from 95 to 100 of specific gravity. Four pounds of the hops were put into the copper when the wort was about 200° of heat, and boiled briskly for the space of twenty minutes; the remaining six pounds were then added, and allowed to boil thirty or forty minutes, according to circumstances. If the gravity of the wort was from 85 to 90, we only made use of eight instead of ten pounds of hops per quarter, boiling four pounds for fifteen minutes, and the remaining four pounds from forty to fifty minutes, as mentioned above. But if the gravity of the wort was only from 70 to 80, seven pounds a quarter only were employed. Two pounds of these were boiled for twenty minutes, and the remaining five pounds put in and boiled for forty or fifty minutes, as before."
"Scottish Ale Brewer", W.H. Roberts, 1847, pages 89-90.

That's nice and clear. Two hop additions, about half from the start of the boil, another 30 or 40 minutes before the end of the boil. That's a much larger late addition than in the English texts.

"These three examples, it must be understood, were first worts, and for high priced ales. When, as in the first example, the whole of the strong ale wort of 95 of gravity is in the copper, and, instead of table beer, an inferior ale is to be produced from the after running, some brewers in Scotland, instead of reboiling the hops, which have had their finer flavour and unctuous principle already drawn off for the strong ale wort, employ fresh hops, which they boil from one hour and a half to one hour and three quarters.

To obtain, however, the remaining properties, as well as the malt extract that the former hops still retain, they either infuse them in hot liquor, which infusion they add to the second ale wort in the copper, or they allow the hops to remain in the hop-back, and run the second ale wort over them from the copper when boiled.

This practice is not so expensive as at first sight it may appear, because not only has the malt extract absorbed by the hops been obtained, but, as much of the remaining valuable parts of the hops have also been extracted, a smaller portion of these is necessary for the second boiling."
"Scottish Ale Brewer", W.H. Roberts, 1847, pages 89-91.

That's a new one. Leaving the hops from the first copper in the hop back and running the second wort over them. Or is that what they call a hop sparge?

"When the wort for the first ale, as in the second example, was 85 to 90, and when, instead of converting the last running of the worts into an inferior ale, it was employed for table beer, the same hops were again boiled with it for two hours. When, as in the third example, the ale wort was only 70 to 80 gravity, the last running was used for small beer instead of table beer; and, in like manner, the same hops were boiled with it for about three hours.

It will be observed, that the quantity of hops we made use of exceeds the proportion generally allowed by Scottish brewers, and that, in the three examples given, no portion of the hops was put into the copper until the wort was within a few degrees of the boiling point; and until this portion had boiled for twenty minutes, the remainder was not added. The result was, that we obtained for the finer ales the more delicate flavour of the hops, while much of the unctuous quality was still left to be imparted to the inferior ales or beers. Neither this, nor reboiling the hops, is the general practice; for many brewers put in the whole of the hops at the time when the wort is pumped into the copper."
"Scottish Ale Brewer", W.H. Roberts, 1847, pages 91-92.

For Small Beer or Table Beer, the hops were re-used. Interesting taht he says this wasn't sytandard practice in Scotland. It's certainly what London brewers often did. And William Younger re-used hops in their weaker Stouts. Neither are two hop additions standard practice. At least according to Roberts. You'll have to decide if you can trust his word or not.

That might be it for hop additions. But, seeing as no-one has screamed at me to stop yet, I might continue.

4 comments:

Graham Wheeler
said...

One thing that is rarely considered with highly-hopped, old beer recipes is that the hop levels specified are often well above the saturation level for iso-alpha acid, even when taking a low-end guess at the alpha content of the hops used. With many of these beers there would be an awful lot of bitterness left behind and wasted if the hops were not reused in a secondary brewing or in the second copper. It is made worse by certain brewing practices of the time.

Books written around the time of Roberts' first edition were to cash in on the effects of the Earl of Liverpool's 'Retail Brewers Act', of 1823, which caused a massive jump from about 1,500 commercial breweries at that time to 36,550 by 1830. The Duke of Wellington's 'Beerhouse Act' of 1830 caused another surge in brewery formations to 49,228. These books were aimed at the small brewers, not the likes of Whitbread.

Most of these breweries were small humble affairs. Even by the early twentieth century the vast majority of breweries had less than a five-quarter mash tun. Probably a one-quarter tun being the most common during the period in question.

They typically had just one wort copper, which often doubled up as a liquor copper. However with a properly proportioned brewery, they would get at least two copper charges per mash with medium-strength beer.

With these breweries there was no facilities for mixing the worts prior to the boil, the second wort was usually being collected in the underback while the first wort was being boiled.

Of course, by far the strongest wort would be the first one, but the practice of apportioning hops according to the strength of the wort (rather than by volume which would have been better), means that most of the hops went into the first copper wort. This first copper is going to be half or even a third of the entire-gyled volume. This will far exceed saturation level even at modest hop rates for the time, and there is no way that an economical bitterness extraction will take place without reboiling the hops in the later worts.

It is difficult to be specific about the actual saturation level, particularly without knowing the alpha-acid content of the hops, but I would say that (at 4% AA) you would be pushing it at much above 4lbs per barrel, bearing in mind that bitterness is related to volume. Of course if you are boiling most of those hops in the first wort at half the final volume your are up to eight lbs/bl which is waaay above saturation. The situation is even worse if the brewer draws three copper charges per mash.

Graham, perhaps brewers were most interested in getting the hop levels in the finished beers right. Putting more hops into the strongest wort because they wanted a bigger hopping rate in the stronger beers.

Barclay Perkins usually went 50%, 25%, 25% with their three coppers. But the situation is more complicated when large amounts of sugar are used. Often the sugar was put into the weaker worts.

Graham, the big London brewers blended just the same way, after the boil. And they also used the coppers sequentially in the same way, boiling the first wort while sparging (or the second mash) were going on. I've never seen anyone bl3end worts pre-boil.

The large, successful brewers weren't just brewing randomly. And they weren't stupid.

I was trying to show why it is sometimes good economics to reuse first wort hops.

There is a limit to how many hops you can shove into a copper and still make a difference due to (iso) alpha acid saturation. Very often the hop rates quoted in recipes exceed that saturation level.

If you take the 15th of August Whitbread PA given at the top of the previous article, the hops are quoted at 5.94 lbs/barrel.

That is 16.5 grams/ litre.If we assume Fuggle at 4.5% AA, that gives 740mg/l alpha acid.

If we then assume a modest 25% utilisation that gives us 185mg/l in the beer; that is an 185 EBU beer. There is no way the beer is going to be that bitter, because the saturation level of iso-alpha acid is about 120mg/l (120 EBU) at most. Some of the potential bitterness is wasted.

They might get away with that if the hop alpha-acid was low and the utilisation was also low, but if that wort was split between three copper charges of equal volume, and 50% of the hop loading was thrown into the first copper as with Barclays, then that first copper is going to be way above saturation level and only a fraction of the potential bitterness will be extracted. The only way to recover that wasted bitterness would be to re-use the hops in something else. Same with late aroma hops that are not boiled for very long; good economics to extract the lost bittering from them in a later copper charge.

As you go back into history the hop rates get much higher, well above saturation, and the situation gets much worse. The absurdity is that one often sees home-brew recipes that attempt to replicate old beers using ridiculous amounts of hops that are just not going to work, for bittering at least.

Small brewers with one copper could blend before the boil by judicious switching the first mash-tun run-off via the spendsafe between the underback (first) and then the copper, so that there is always some strong wort being held in the underback for use in later copper charges. Some even had two underbacks. Not very efficient time wise or vessel utilisation wise, because much of the first run off is going to the underback while the copper is waiting, but fine for regionals that mash just once a day.

I am sure that even on here you have quoted articles that point out the advantages of boiling strong worts over weak ones. Not everything was done the Barclay Perkins way. Adding the sugar to the weakest wort makes sense, but it only needs to be boiled for long enough to dissolve and sterilise it.

Most regionals would stop sparging when the gravity of the spargings fell below about 1.010 or 1.008, but the big London brewers seemed to be reluctant to let even that extract get away from them.

With some of the blending specified on here, the weakest wort after the boil has been not much stronger than water, say umpteen barrels at 1.005, which means they must sparge their mash right down to water. I would suspect that much of the complicated pre-fermentation blending that went on was to use up that last little bit of extract, whereas a small regional would probably have thought it not worth the trouble.